1. Field of the Invention
The invention relates to a coordinate measuring instrument or a machining equipment, and more particularly to such an instrument or equipment with a component that is mounted movably on two guides at its one end by means of a component foot.
2. Discussion of Relevant Art
A coordinate measuring instrument of this kind is known, for example, from German Patent DE 40 26 990 A1. This concerns a so-called column measuring instrument, in which the said component is a vertically aligned column. There is mounted on the column a horizontally movable measuring arm that is additionally mounted on a cross-slide that is displaceable vertically on the column. A feeler pin attached to the end of the measuring arm can thus be displaced in two mutually perpendicular coordinate measuring directions. In order to be able to move the feeler pin in the third coordinate direction perpendicular to the other coordinate measuring directions, a column foot is attached to the column and is movably guided on the end surface of a measuring table on two spaced-apart guides.
Since the guides cannot be attached to the end of the measuring table exactly parallel within the range of production accuracies, rotation errors of the column thus arise and result in a variation of the vertical alignment of the column in dependence on the alignment of the guides. It was therefore already proposed in German Patent DE 40 26 990 A1 to provide variably adjustable elements by means of which the distance of the guides from the end of the measuring plate can be altered, in order thereby to adjust the guides so that the guides are aligned nearly parallel and the rotation errors no longer arise.
An adjustment of this kind, in which the distance of the guides from the measuring plate has to be set, is however very expensive in time and thus in cost.
The present invention therefore has as its object to propose a coordinate measuring instrument or a machining equipment, with which the rotation errors can be corrected in a simple manner. The object is attained according to the invention in that the component foot is arranged so that the component turns in a plane which lies orthogonally to the direction of motion when the distance between the guides is altered.
The particular advantage of the coordinate measuring instrument according to the invention is that only the distance between the guides has to be correspondingly set in order to compensate for the rotation error. This is considerably simpler than adjusting the distance of the guides from the measuring plate, since the adjustment can now take place transversely of the direction of attachment to the measuring plate. Thus the two guides can firstly be fastened precisely and parallel to each other, and thereafter one of the two guides can be adjusted so that the distance of the guides is correspondingly set.
In order to obtain this functionality, the component foot has at least one extension arm that is mounted movably relative to the component and is supported on a first of the two guides.
In a particularly preferred embodiment, the extension arm is connected to the component foot by means of a joint, and in fact such that when the distance between the guides is reduced, forces arise that lead to a rotation of the component concerned. Ball joints are candidates as joints here as well as the usual hinges.
The rotation of the component or of the component foot takes place around a joint in the region of the second guide. This is possible, for example, when the component foot has, at a distance from the second guide, at least one corresponding joint by means of which the column is rotatably mounted on the second guide. However, this is also possible when, as described hereinbelow in further detail, the component can itself be directly rotated around the guide, which is possible, for example, when the guide includes a rail and at least one revolving ball shoe, movably mounted on the rail since revolving ball shoes can be rotated in a small angle range about the rails.
Also the extension arm must be additionally mounted in the region of the first guide, for rotational movement. This can take place, as already stated above, either by the extension arm being rotatably guided directly on the rail, or by the extension arm having an additional joint which is provided in the region of the guide.
However, it is not imperatively necessary for the extension arm to be rotatably connected to the component foot, as is the case in the first embodiment example described above. In another variant, not shown here in more detail, it is only necessary for the component to be rotatably mounted on the said second guide. The extension arm can here be mounted completely rigidly on the first guide and can cooperate, by means of a correspondingly curved running surface, with an obliquely formed surface of the component, such that when the distance between the two guides is reduced, the curved surface is pushed like a wedge under the curved, tapered surface of the component and the component is thereby turned. In order to be able to rotate the component in the other direction also, the curved surface and the tapered surface are pulled together, for example by means of mechanical clamping, or by means of magnets.
Any guides, such as for example air bearing guides, slideways, or rolling guides can of course be used as the guides. As already stated hereinabove, the guides however include, in a particularly advantageous embodiment, revolving ball shoes and rails on which the revolving ball shoes are guided. These have the particular advantage that the revolving ball shoes are permitted a rotation through a small angle of rotation about the longitudinal axis of the rail, so that in particular a rotary joint on the second guide for a rotation of the component can be dispensed with. The alignment of the two guides is completely unimportant here. For example, the guides can be attached to the end of a measuring table, as already described in connection with DE 40 26 990 A1. They can of course just as well be fastened to the upper side of the measuring table, to a wall, to the floor of the space, to a column, etc.
Very different variants are also conceivable as the component. For example, the cross slide shown in DE 40 26 990 A1 and provided for carrying the measuring arm could just as well be guided on the column of the column measuring instrument by means of the described construction. Also, the measuring arm could be guided on the cross slide, in which case the guide rails would be fastened to the measuring arm.